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Swingarms are exclusive to two-wheelers – but what do they do?
And why do some motorcycles have just one swingarm while others have two? Are there any advantages to bikes with just one swingarm?
Tune in to discover:
- What a swingarm is, and what it does
- Differences between “single-sided” and “double-sided” swingarms
- How the length of your swingarm matters
Transcript
Hello, and welcome to another episode of 30-minute motorcycling – a podcast for those riders who are at the beginning of their own Dual Wheel Journey, where you’ll discover something new about how your motorcycle, moped, or scooter works – in less than 30 minutes.
In addition to a shock absorber at the rear, your motorcycle or scooter’s rear suspension also has something called a “swingarm” – something which is unique to two-wheelers.
And this episode is all about those – we’re going to talk more about:
- What a swingarm is, and what it does
- Differences between single and double-sided swingarms
- And how the length of the swingarm matters
So, what is a swingarm?
A swingarm is a movable joint shaped like the letter “L” or “H” that’s a part of your suspension setup.
If your bike didn’t have a swing arm, the rear suspension would have no support, and the same thing can be said for your rear wheel.
Although it can sometimes be hard to see, the swingarm is found at the rear – with one end attached to the rear wheel and the other end attached to the main frame through the “swingarm pivot bolt.”
On a motorcycle with shaft drive, such as many BMWs, the housing for the shaft acts as a swingarm.
Either way, this swingarm pivot bolt makes it possible for the rear wheel to move up and down.
One last thing – although the bearings for swingarms are strong, if they’re worn out, your bike might feel a bit unstable to ride.
It’s for this reason that some motorcycles have grease nipples for the swingarm bolts – remember to lube these up regularly – especially if you ride off-road a lot.
So now that we’ve covered what a swingarm does, let’s move on single vs. double sided swing arms.
At a very basic level, motorcycles and scooters with just one swingarm has a “single-sided swingarm” setup – while one with two swingarms have a “double-sided swingarm” setup.
Obviously, right? But there’s more it than you might think – for example, why do some bikes only have one swingarm?
It’s not all about style – bikes with a single sided swingarm setup have less unsprung weight compared to ones with double-sided swingarms – and since you want to keep unsprung weight to a minimum, this is a good thing.
By the way, if you’d like to discover more about unsprung weight, please check out episode 24 of this podcast.
Anyway, in addition to a lower unsprung weight, it’s also easier and certainly quicker to remove a rear wheel from a motorcycle with a single-sided swingarm.
So why don’t all motorcycles have single-sided swingarms, then?
Because although it’s technically easier to remove a wheel from a single-sided swingarm bike, if your bike doesn’t have a center stand, it’s also harder, since you’ll need a paddock stand to do this.
So that’s single-sided swingarms vs. double-sided swingarms. Let’s now move onto swingarm length – which certainly does matter.
The key thing to remember about swing arm length is this – the further forward the swingarm is, the further forward the bike’s overall center of gravity is.
This is why motorcycles used for drag racing have extended swingarms – they prevent the bike from popping a wheelie at the start during quick accelerations.
And that’s the topic of swingarms, what they do, and the differences between single- and double-sided swingarms.
Thank you for listening – I hope that you enjoyed this episode, and above all, that you discovered something new.
Until next time, keep your helmet on, and your eyes on the road. Bye!
